PROGETTAZIONE E PROTOTIPAZIONE DI UNO STRUMENTO MECCATRONICO PER LA CORREZIONE AUTOMATICA DEI MOVIMENTI INVOLONTARI IN MICROCHIRURGIA

Italiano: Questa tesi si è proposta di progettare, integrare e costruire il prototipo di un bisturi meccatronico, uno strumento attivo per la cancellazione del tremore fisiologico del chirurgo impegnato in operazioni oftalmiche, che presenta il vantaggio di mantenere una forma di chirurgia diretta, rilevando il movimento imposto dalla mano del medico e compensandone attivamente le componenti indesiderate. E' stata, inoltre, definita la sensoristica da alloggiare all'interno dello strumento meccatronico e si è provveduto a caratterizzare, tramite l'utilizzo di due banchi prova appositamente progettati e costruiti, il segnale di due giroscopi e di un accelerometro triassiale scelti per la rilevazione del movimento. Il bisturi riesce a soddisfare le specifiche fisiologiche individuate, anche grazie a un nuovo sistema ibrido di attuazione interna, in cui un'amplificazione meccanica e una di tipo idraulico sono abbinate ad attuatori piezoelettrici. In particolare test preliminari hanno mostrato che lo strumento è in grado di compensare componenti di moto di ampiezza pari a oltre 500 \u3bcm e contenuto in frequenza fino a 60 Hz. Il lavoro svolto costituisce la base per una serie di prossimi esperimenti atti a validare l'efficacia di questo strumento. English: The aim of this thesis was to design, integrate and fabricate a handheld microsurgical mechatronic instrument. The device is intended to be exploited for active suppression of physiological tremor, which limits the accuracy during ophthalmic and neurological microsurgery. The working principle is to detect the surgeon's hand movement and to compensate involuntary components. A dedicated setup has been developed for characterisation of the 2 microelectromechanical gyroscopes and of the triaxial accelerometer which are adopted for motion detection. The tool meets the requirements given by the medical applications, thanks mainly to a new hybrid concept for internal actuation, where mechanical and hydraulic amplifications are coupled with piezoelectric actuators. In particular preliminary tests proved that the device is able to compensate motion components whose maximum amplitude is greater than 500 \u3bcm and frequency content is up to 60 Hz. This work is the basis for future experiments aimed at assessing the effectiveness of the tool

Effects of non-pharmacological or pharmacological interventions on cognition and brain plasticity of aging individuals.

Brain aging and aging-related neurodegenerative disorders are major health challenges faced by modern societies. Brain aging is associated with cognitive and functional decline and represents the favourable background for the onset and development of dementia. Brain aging is associated with early and subtle anatomo-functional physiological changes that often precede the appearance of clinical signs of cognitive decline. Neuroimaging approaches unveiled the functional correlates of these alterations and helped in the identification of therapeutic targets that can be potentially useful in counteracting age-dependent cognitive decline. A growing body of evidence supports the notion that cognitive stimulation and aerobic training can preserve and enhance operational skills in elderly individuals as well as reduce the incidence of dementia. This review aims at providing an extensive and critical overview of the most recent data that support the efficacy of non-pharmacological and pharmacological interventions aimed at enhancing cognition and brain plasticity in healthy elderly individuals as well as delaying the cognitive decline associated with dementia

Elevated plasma ceramide levels in post-menopausal women: a cross-sectional study.

Circulating ceramide levels are abnormally elevated in age-dependent pathologies such as cardiovascular diseases, obesity and Alzheimer's disease. Nevertheless, the potential impact of age on plasma ceramide levels has not yet been systematically examined. In the present study, we quantified a focused panel of plasma ceramides and dihydroceramides in a cohort of 164 subjects (84 women) 19 to 80 years of age. After adjusting for potential confounders, multivariable linear regression analysis revealed a positive association between age and ceramide (d18:1/24:0) (β (SE) = 5.67 (2.38); p = .0198) and ceramide (d18:1/24:1) (β (SE) = 2.88 (.61); p < .0001) in women, and between age and ceramide (d18:1/24:1) in men (β (SE) = 1.86 (.77); p = .0179). In women of all ages, but not men, plasma ceramide (d18:1/24:1) was negatively correlated with plasma estradiol (r = -0.294; p = .007). Finally, in vitro experiments in human cancer cells expressing estrogen receptors showed that incubation with estradiol (10 nM, 24 h) significantly decreased ceramide accumulation. Together, the results suggest that aging is associated with an increase in circulating ceramide levels, which in post-menopausal women is at least partially associated with lower estradiol levels

The pharmacological perturbation of brain zinc impairs BDNF-related signaling and the cognitive performances of young mice.

Zinc (Zn2+) is a pleiotropic modulator of the neuronal and brain activity. The disruption of intraneuronal Zn2+ levels triggers neurotoxic processes and affects neuronal functioning. In this study, we investigated how the pharmacological modulation of brain Zn2+ affects synaptic plasticity and cognition in wild-type mice. To manipulate brain Zn2+ levels, we employed the Zn2+ (and copper) chelator 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol, CQ). CQ was administered for two weeks to 2.5-month-old (m.o.) mice, and effects studied on BDNF-related signaling, metalloproteinase activity as well as learning and memory performances. CQ treatment was found to negatively affect short- and long-term memory performances. The CQ-driven perturbation of brain Zn2+ was found to reduce levels of BDNF, synaptic plasticity-related proteins and dendritic spine density in vivo. Our study highlights the importance of choosing "when", "where", and "how much" in the modulation of brain Zn2+ levels. Our findings confirm the importance of targeting Zn2+ as a therapeutic approach against neurodegenerative conditions but, at the same time, underscore the potential drawbacks of reducing brain Zn2+ availability upon the early stages of development

A Stage-Based Approach to Therapy in Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder that features progressive, disabling motor symptoms, such as bradykinesia, rigidity, and resting tremor. Nevertheless, some non-motor symptoms, including depression, REM sleep behavior disorder, and olfactive impairment, are even earlier features of PD. At later stages, apathy, impulse control disorder, neuropsychiatric disturbances, and cognitive impairment can present, and they often become a heavy burden for both patients and caregivers. Indeed, PD increasingly compromises activities of daily life, even though a high variability in clinical presentation can be observed among people affected. Nowadays, symptomatic drugs and non-pharmaceutical treatments represent the best therapeutic options to improve quality of life in PD patients. The aim of the present review is to provide a practical, stage-based guide to pharmacological management of both motor and non-motor symptoms of PD. Furthermore, warning about drug side effects, contraindications, as well as dosage and methods of administration, are highlighted here, to help the physician in yielding the best therapeutic strategies for each symptom and condition in patients with PD

The mitochondrial Na+/Ca2+ exchanger upregulates glucose dependent Ca2+ signalling linked to insulin secretion.

Mitochondria mediate dual metabolic and Ca(2+) shuttling activities. While the former is required for Ca(2+) signalling linked to insulin secretion, the role of the latter in β cell function has not been well understood, primarily because the molecular identity of the mitochondrial Ca(2+) transporters were elusive and the selectivity of their inhibitors was questionable. This study focuses on NCLX, the recently discovered mitochondrial Na(+)/Ca(2+) exchanger that is linked to Ca(2+) signalling in MIN6 and primary β cells. Suppression either of NCLX expression, using a siRNA construct (siNCLX) or of its activity, by a dominant negative construct (dnNCLX), enhanced mitochondrial Ca(2+) influx and blocked efflux induced by glucose or by cell depolarization. In addition, NCLX regulated basal, but not glucose-dependent changes, in metabolic rate, mitochondrial membrane potential and mitochondrial resting Ca(2+). Importantly, NCLX controlled the rate and amplitude of cytosolic Ca(2+) changes induced by depolarization or high glucose, indicating that NCLX is a critical and rate limiting component in the cross talk between mitochondrial and plasma membrane Ca(2+) signalling. Finally, knockdown of NCLX expression was followed by a delay in glucose-dependent insulin secretion. These findings suggest that the mitochondrial Na(+)/Ca(2+) exchanger, NCLX, shapes glucose-dependent mitochondrial and cytosolic Ca(2+) signals thereby regulating the temporal pattern of insulin secretion in β cells

Inhibition of de novo ceramide biosynthesis affects aging phenotype in an in vitro model of neuronal senescence.

Although aging is considered to be an unavoidable event, recent experimental evidence suggests that the process can be counteracted. Intracellular calcium (Ca2+i) dyshomeostasis, mitochondrial dysfunction, oxidative stress, and lipid dysregulation are critical factors that contribute to senescence-related processes. Ceramides, a pleiotropic class of sphingolipids, are important mediators of cellular senescence, but their role in neuronal aging is still largely unexplored. In this study, we investigated the effects of L-cycloserine (L-CS), an inhibitor of thede novoceramide biosynthesis, on the aging phenotype of cortical neurons cultured for 22 days, a setting employed as anin vitromodel of senescence. Our findings indicate that, compared to control cultures, 'aged' neurons display dysregulation of [Ca2+]ilevels, mitochondrial dysfunction, increased generation of reactive oxygen species (ROS), altered synaptic activity as well as the activation of neuronal death-related molecules. Treatment with L-CS positively affected the senescent phenotype, a result associated with recovery of neuronal [Ca2+]isignaling and reduction of mitochondrial dysfunction and ROS generation. The results suggest that thede novoceramide biosynthesis represents a critical intermediate in the molecular and functional cascade leading to neuronal senescence and identify ceramide biosynthesis inhibitors as promising pharmacological tools to decrease age-related neuronal dysfunctions

Influence of APOE and RNF219 on Behavioral and Cognitive Features of Female Patients Affected by Mild Cognitive Impairment or Alzheimer's Disease.

The risk for Alzheimer's disease (AD) is associated with the presence of the ?4 allele of Apolipoprotein E (APOE) gene and, recently, with a novel genetic variant of the RNF219 gene. This study aimed at evaluating interactions between APOE-?4 and RNF219/G variants in the modulation of behavioral and cognitive features of two cohorts of patients suffering from mild cognitive impairment (MCI) or AD. We enrolled a total of 173 female MCI or AD patients (83 MCI; 90 AD). Subjects were screened with a comprehensive set of neuropsychological evaluations and genotyped for the APOE and RNF219 polymorphic variants. Analysis of covariance was performed to assess the main and interaction effects of APOE and RNF219 genotypes on the cognitive and behavioral scores. The analysis revealed that the simultaneous presence of APOE-?4 and RNF219/G variants results in significant effects on specific neuropsychiatric scores in MCI and AD patients. In MCI patients, RNF219 and APOE variants worked together to impact the levels of anxiety negatively. Similarly, in AD patients, the RNF219 variants were found to be associated with increased anxiety levels. Our data indicate a novel synergistic activity APOE and RNF219 in the modulation of behavioral traits of female MCI and AD patients